Drill bit for producing an irregular indentation pattern on the bottom of a well bore



Jan. 30, 1962 c M KUCERA 3,018,835

DRILL BIT FOR PRODiICfNG AN IRREGULAR INDENTATION Filed Nov. 1, 1956PATTERN 0N THE-{3OTTOM OF A WELL BORE v -2 Sheets-Sheet 1 C/emewz M KuCW INVENTOR.

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ATTO/P/VEVJ Jan. 30, 1962 c. M. KUCERA 3,018,835 DRILL BIT FOR PRODUCINGAN IRREGULAR INDENTATION V PATTERN ON THE BOTTOM OF A WELL BORE FiledNov. 1, 1956 2 Sheets-Sheet 2 67607602 M. flue-era INVEN'TOR.

ATTOR/VE m 3,018,835 Patented Jan. 30, 1962 3,018,835 DRILL BIT FORPRODUCING AN IRREGULAR INDENTATION PATTERN ON THE BQTTOM OF A WELL BOREClement M. Kucera, Houston, Tex., assignor to Reed Roller Bit Company,Houston, Tex., a corporation of Texas Filed Nov. 1, 1956, Ser. No.619,808 3 Claims. (Cl. 175-378) This invention relates generally todrill bits for deep wells and more particularly to the arrangement ofteeth on the cutters of roller type drill bits.

In the drilling of wells with roller type drill bits, the roller cuttersare rolled around on the bottom of the hole being drilled. The rollercutter teeth may thus form indentations, with projecting rock teeththerebetween, in the earth formation being encountered. Theseindentations may be gradually deepened upon successive rounds by theroller cutter to a magnitude where the roller cutter teeth intermeshwith the indentations in the formation in a manner similar to a gear,whereupon the progress of the drill bit through the formation may beimpaired.

It is an object of this invention to provide a new and improved drillbit roller cutter which will during the operation thereof tend toalleviate the formation of projecting rock teeth on the bottom of a borehole.

Another object is to provide a new and improved arrangement of teeth fora drill bit roller which during the operation thereof will produce anirregular indentation pattern on the bottom of a hole being drilled bythe drill bit.

Another object is to provide a drill bit roller cutter having rows ofcutting teeth thereon wherein in at least one of the said rows of teeth,at least one tooth will have an extremely wide crest to serve as acrushing element to break up projecting ridges of formation which may beformed on the bottom of a bore hole by the other teeth in the same row,or by the teeth of the other cutters on the drill bit.

Another object is to provide a drill bit having new and improved rollercutters thereon to enhance the rate of penetration of the drill bit.

Other objects will become apparent from the following descriptions andaccompanying drawings, in which:

FIG. 1 is an isometric view of a drill bit employing cone-type rollercutters.

FIG. 2 is a bottom plan view of a cone-type drill bit employing thecutters of the invention.

FIG. 3 is a detail view of an approximately conical roller cutter havingrows of teeth arranged in accordance with the invention.

FIG. 4 is a diagrammatic view illustrating how the cutter teeth operateon the formation being drilled.

Referring to FIG. 1, a three-cutter drill bit is shown generally at A.It has a bit head 1 and the usual threaded shank 2 adapted forconnection to the lower end of a drill stem (not shown). The bit head 1has a plurality of depending bearing extensions 3 upon which arerotatably mounted roller cutters 4, 5 and 6.

The cutter 4 has an outer row of teeth 7; an intermediate row of teeth8; and an inner row of teeth 9. The outer row of teeth 7 has an enlargedtooth 10 and a plurality of conventional chisel-type teeth 28. As shown,the conventional teeth 28 are consecutively arranged in a group (orsets) and have generally uniform crests. The crest of the tooth 10 has awidth approximately equal to the pitch distance between the conventionalteeth 28 of the rOW 7.

The cutter 6 has an outer row of teeth 11 which contains an enlargedtooth 12 and a plurality of conventional teeth 29. The crest width ofthe tooth 12 is approximately equal to one and one-half times the pitchdistance between the teeth 29 in the row 11.

The cutter 5 has rows of teeth 33 substantially conventional in form.

Referring to FIG. 2, a drill bit similar to that shown in FIG. 1 isillustrated. The bit has a head 13 upon which are rotatably mountedroller cutters 14, 15 and 16. Since all of the cutters of the inventionshown on the drawings operate in a similar manner, a description of onewill describe the others.

FIG. 3 is a detail view of the cutter 15 shown in FIG. 2. The cutter 15has an outer row of teeth '17; an intermediate row of teeth 18; and aninner row of teeth 19. The outer row of teeth 17 has at least oneenlarged tooth 20 the crest of which has a width, for example, equal toapproximately twice the pitch distance between the conventional teeth 30in the row 17. It is to be understood that the crest width of the tooth20 may be varied as desired; however, I prefer to have the crest widthof the tooth 20 equal to approximately one-half to two times the pitchdistance of the teeth 30 in the row 17, it being understood that morethan one enlarged tooth may be contained in the row if desired.

The intermediate row of teeth 18 has a wide crested tooth 21 and aplurality of conventional teeth 31, and the inner row of teeth 19 has aWide crested tooth 22 and a plurality of conventional teeth 32.

FIG. 4 illustrates the action of the cutters of the invention on theformation. When the sets of conventional cutter teeth 23 penetrate theformation, they leave indentations 24 and projecting ridges or rockteeth 25 therebetween. When these rock teeth 25 are encountered by thewide crested tooth 26, the rock teeth 25 are substantially crushed asindicated at 27, thus removing some of the formation and producing anirregular pattern in the formation being drilled.

The invention is not confined to the embodiments shown and described.Various changes, within the scope of the following claims, will becomeapparent to those skilled in the art.

I claim:

1. The drill bit having a plurality of rotatable cutters mountedthereon, each of the said cutters having circumferential rows of cuttingteeth thereon, at least one of the said rows of cutting teeth on atleast one of the cutters comprising a set of conventional chisel shapedteeth arranged consecutively and having a substantially uniform pitchand tooth crest, and at least one tooth having a crest width extendingaxially for a distance substantially equal to the width of the row asWell as extending circumferentially and equal to at least half the pitchdistance of the conventional teeth in the same row, to produce anirregular pattern on the bottom of the hole being drilled.

2. A drill bit having a plurality of rotatable cutters mounted thereon,each of the said cutters having circumferential rows of cutting teeththereon, at least one row of cutting teeth on at least one of the 'saidcutters having groups of consecutively arranged chisel type teeth and anenlarged crested tooth between each of the said groups of conventionalteeth in the same row, the crest of said enlarged tooth extendingaxially for a distance substantially equal to the Width of the row aswell as extending circumferentially of the row for a distancesubstantially equal to at least one-half to two times the pitch distanceof the said chisel type teeth.

3. A drill bit having a rotatable cutter thereon, the said cutter havingcircumferential rows of teeth thereon, at least one of the said rows ofteeth comprising sets of an irregular pattern on the bottom of the holebeing drilled.

References Cited in the file of this patent UNITED STATES PATENTS ScottFeb. 7, 1933 Rogatz Jan. 14, 1936 Smith et al. Oct. 5, 1937 Peter Aug.21, 1956

